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Discussion Starter · #1 ·
I have a few questions about triumph pushrod tubes that maybe somebody can help with (the haynes manual sure couldn't). The tubes on my '70 are the correct ones for that motor. On the bottom, they push down on the thick, white seal and have a seperate ring that goes around the seal to keep it from squishing out. My other bike has two different types of tubes and they both leak like a siv. the back one has a flared skirt at the bottom that seems to contact the base of the barrel, leaving a pretty big gap where the white seal is supposed to go. The front one doesn't have the skirt like the rear, but it also doesn't look like the ones on the '70. I know that the recess in the head for the pushrod tube is different for later 650s and that those tubes are slightly longer and won't work with an early head. That being said, here are my questions:

1. Is there any way to tell which head I have other than pulling it all apart?

2. Is the sealing area on the base of the jugs the same for early and late unit 650s?

3. How many different style pushrod tubes are there for unit 650s?

Thanks
Jake
 

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I just assembled my basketcase unit 650 with a '67 bottom end and '71 head. It had two different pushrod tubes for intake and exhaust. One had a castellated top, the other had holes drilled around the circumference. Both measured the same length between the two shoulders for the bottom and top seals.
Make sure you use the correct seals. My gasket set had different thicknesses for the square white seal at the bottom of the tube, the top seals are just o-rings. Once you push the tubes and bottom seals down on the tappet block and set the head on top (top seals in place), you should have .080" crush (gap between head and head gasket). Less and you won't get a good seal, more and you could damage the pushrod tubes. That's what my Triumph guy told me.

Mike
 

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Another chapter in the basket case blues

Pushrod tubes, lifter blocks and the o-rings for them are like axles and triple trees only worse. Three or four different styles of 650 unit pushrod tubes, several, I think three different shaped and surfaced lifter blocks and three or four different recesses in the head of the Triumphs 1963 to 1970 make for a bitch of a time when you have mixed and matched stuff.

The rule is as follows with mix and match stuff. You need to set up the "squish" in the head. Use what ever combination of tubes and o-rings (there are three different sizes plus o-rings that are specifically designed to go into recesses inside the tube) so that you can stick a 1/16 of an inch drill bit between the head gasket and the underside surface of the head and see that much light between the head and barrel. This allows the most effective "squish" to occur. I always cheat and use Yamabond or 1104 or whatever hi-temp semi-drying substance is your favorite as well to hedge my bets. Use semi-dry because hardning will just get hard and crusty when the motor gets hot and flake off.

there are some exceptions to this otherwise iron law of head squish. Some pushrod tubes simply will not work with some lifter block surface/head recess combinations, so if you have multiple sets, you might have to use them.
 

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Discussion Starter · #4 ·
thanks for the info guys...although you were supposed to say "its easy, you can put any tube on any motor with any seal." i've got all the different types of seals and o-rings ever used, now i need to collect all the tubes i guess...

thanks again
jake
 
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